<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            display: flex;
            justify-content: center;
        }

        div {
            display: flex;
            /* 默认不换行 */
            /* flex-wrap: nowrap; */
            /* 换行 */
            flex-wrap: wrap;
            height: 400px;
            width: 500px;
            background-color: pink;
        }

        div span {
            height: 50px;
            width: 200px;
            background-color: purple;
        }
    </style>
</head>

<body>
    <div><span>1</span><span>2</span><span>3</span><span>4</span></div>
</body>

</html>